In order to maintain the competitiveness of the third generation mobile communication system in the field of communication, to provide mobile communication services with faster speed, lower delay and more personalization for users, and meanwhile to reduce the operator's operating costs, the third Generation Partnership Project (3GPP) standard working group is committing to the research of the Evolved Packet System (EPS). FIG. 1 is a schematic diagram of structure of the EPS, and as shown in FIG. 1, the whole EPS is divided into two parts: the radio access network and the core network. The core network comprises Home Subscriber Server (HSS) 101, Mobility Management Entity (MME) 102, Serving General Packet Radio Service (GPRS) Support Node (SGSN) 103, Policy and Charging Rule Function (PCRF) 104, Serving Gateway (S-GW) 105, PDN Gateway (P-GW) 106 and Packet Data Network (PDN) 107. The functions of each part are as follows.
The HSS 101 is the permanent storage site of user subscription data and is located in the user subscribed home network.
The MME 102 is the storage site of the user subscription data in the current located network and is responsible for the non-access stratum signaling management from the user equipment to the network, the security verification function of the user equipment, the mobility management of the user equipment, tracking and paging management function in the idle mode of the user equipment as well as bearer management.
The SGSN 103 is the serving support node for the user equipment accessing the core network in the GSM EDGE Radio Access Network (GERAN) and the Universal Terrestrial Radio Access Network (UTRAN), and its function is similar to the MME 102 and is responsible for functions of location update, paging management, and bearer management etc. of the user equipment.
The S-GW 105 is the gateway from the core network to the ratio access network and is responsible for functions of the user plane bearer from the user equipment to the core network, data cache in the idle mode of the user equipment, the network side initiating a service request, and functions of legal interception, packet data routing and forwarding; and it is responsible for performing statistic of the situation of the user equipment using the radio access network, generating the bill of the user equipment using the radio access network, and transmitting the bill to the charging gateway.
The P-GW 106 is the gateway for the EPS interacting with the external PDN 107 of the EPS, it is respectively connected to the Internet and the PDN 107, and is responsible for functions of the user equipment's Internet Protocol (IP) address allocation, charging function, packet filtering, and strategy control, and so on.
The PDN 107 is the operator's IP service network, and it provides IP service to the user equipments via the operator's core network.
The PCRF 104 is the server responsible for providing rules of charging control, online credit control, threshold control, and quality of service (QoS) strategies and so on in the EPS.
The radio access network is composed of the E-UTRAN NodeB (eNB) 111 and the third-generation (3G) Radio Network Controller (RNC) 112, and it is mainly responsible for sending and receiving radio signals, interacting with the user equipment via the air interface, managing the radio resource, resource scheduling and access control of the air interface and so on.
The above SGSN 103 is an upgraded SGSN, and it can support the S4 interface with the S-GW 105 and interconnects with MME 102 using the GPRS Tunneling Protocol (GTP) v2. However, for the SGSN 103 supporting the 3G core network, the PS domain network architecture is different from that in FIG. 1, and at this point, the SGSN 103 and the MME 102 connect via the Gn interface and interconnect using the GTPv1; the SGSN 103 cannot connect with the S-GW 105 and directly accesses the PDN 107 by connecting the Gateway GPRS Support Node (GGSN) via the Gn interface.
The Home NodeB (HNB) or the Home eNodeB (HeNB) is a class of miniature and low-power NodeBs, acts as the dedicated resources of certain users, is deployed in private places such as homes, groups, companies or schools for use, and is mainly for providing higher service speed for users and reducing the cost needed in using the high-speed services and meanwhile making up the lack of the coverage of the existing distributed cellular radio communication systems. The HNB has the advantages of affordable, convenient, low-power output, plug and play, broadband access, and using single-mode terminals, and so on.
The Home NodeB can be applied in the 3G or Long Term Evolution (LTE) mobile communication network. In order to facilitate the management of the home NodeB, a new network element, namely the HNB gateway, is introduced into the mobile communication network. The main functions performed by the HNB gateway are: verifying the security of the Home NodeB, maintaining and managing the operation of the HNB, configuring and controlling the HNB according to the operator's requirements, and exchanging data information between the core network and the HNB.
FIG. 2 is a schematic diagram of the network architecture of the 3G HNB, as shown in FIG. 2, the 3G home NodeB (HNB) 201 connects to the HNB gateway (HNB GW) 202 via the newly defined luh interface, and the HNB GW 202 provides the luPS interface to the packet domain and the luCS interface to the circuit domain in the core network. For the 3G mobile communication network, the HNB GW 202 is a required deployment to shield the effects to the user equipment and network side after introducing the HNB 201.
For the LTE mobile communication network, the HeNB GW is an optional deployment, and therefore, there are two methods for connecting the LTE HeNB and the core network; one is that the HeNB 301 directly connects with network elements in the core network, as shown in FIG. 3; the other is that the HeNB 401 connects with network elements in the core network via the HeNB GW 402, as shown in FIG. 4A. For the scenario of introducing the HNB gateway as shown in FIG. 4A, the HeNB gateway might not integrate the user plane functions, and the user plane is established directly between the HeNB gateway and the user plane gateway of the core network, which enable to flatten the user plane and decrease the data transmission delay, and its structure is shown as FIG. 4B.
Besides supporting to access the core network, the HNB might also support the local IP access (LIPA) function, under the condition that the HNB has the local IP access capability and the user subscription allows the local IP access, the local access of the user to other IP devices in the home network or the Internet can be implemented, and the other IP devices are devices except the user equipment in the home network. With the local IP access function, the Internet data service offload can be implemented, so as to reduce the load of the core network, and the access to the devices in the home network can be forwarded without passing the core network, and the data transmission is convenient and efficient.
The local IP access function might also be applied in the macro cell or the HNB GW, its main purpose is similar to the HNB, and it is applied more in such a scenario that the local IP accesses Internet, so as to reduce the load of the core network.
FIG. 5 is a schematic diagram of a method for implementing the local IP access function, as shown in FIG. 5, the data sent by the user equipment 501 to the home network 502, the Internet 503 and the core network 504 can share the same PDN connection, the data offload function unit in the radio side network elements 505 can fulfill the selection of the data packet routing, the Network Address Translation (NAT) function unit 506 translates the user internal address to the outside. The data offload function unit and the NAT function unit 506 might be deployed with the NodeB (such as HNB, and macro NodeB) together or the HNB gateway, or might be deployed separately.
Currently, there is no definite solution of the method for acquiring the routing strategies applied by the data offload function unit in the radio side network elements.